Array/ Array list/ Linked list

How can we eradicate duplicated value in array?

1. Set

• Set does not allow duplication
• convert array into set

💡 Set https://soheeparklee.github.io/posts/DS-list_set_map/

2. For loop

• 배열을 돌면서 중복되는 값 삭제

3. Array.sort

• 배열을 오름차순/내림차순으로 정렬
• 옆에 있는 값끼리 비교해서 같으면 삭제

4. Stream API

• use stream to delete duplicated value
• stream API is added from JAVA 8

Array 🆚 Array List 🆚 Linked List

✔️ Array

• 👍🏻 can access directly with index to element
  • time complexity: O(1)
• 👎🏻 need to fix size while creating

✔️ Array List(Array)

• use dynamic array to store data
• 👍🏻 dynamic
• 👍🏻 has list, can access directly
• 👍🏻 fast in searching data
• insertion, deletion slow

Why slow in insertion, deletion?

데이터 추가 및 삭제 때 데이터를 재할당한다.
thus, insertion and deletion slower than array

✔️ Linked List(Node)

• use doubly linked list to store data
• 👍🏻 dynamic: do not need to fix size
• 👍🏻 insertion, deletion easy
  • has address that saves the location of previous, next nodes
  • for insertion, deletion, just need to change value of previous, next node
• 👎🏻 cannot access directly, need to search from head

📌 Q&A

Why use array, instead of linked list?

fast in search
can access element using index

When to use array, when to use linked list?

array: search
linked list: insertion, deletion

💡 Reference

https://soheeparklee.github.io/posts/JAVA_list/
https://soheeparklee.github.io/posts/JAVA_collectionFramework/